Electro-hydraulic control system



Aug. 1, 1967 J. MERCIER ETAL ELECTRO-HYDRAULIC CONTROL SYSTEM 2 Sheets-Sheet 1 Filed Deo. 28, 1966 oak/M40 Maze/5e BY Aug. 1, 1967 J. MERCIER ETAL ELECTRO-HYDRAULIC CONTROL SYSTEM 2 Sheets-Sheet Filed Dec. 28, 1966 L53 INVENTQR 5 7:441 M 62 case ATTORNEY United States Patent 3,333,413 ELECTRO-HYDRAULIC CONTROL SYSTEM Jean Mercier, 501 Bloomfield Ave., Caldwell, NJ. 07006, and Bernard Mercier, 12287 Osborne St., Pacoima, Calif. 91331 Filed Dec. 28, 1966, Ser. No. 605,489 7 Claims. (Cl. 60--10.5)

This application is a continuation-impart of copending application Ser. No. 374,451, filed June 11, 1964, now Patent No. 3,304,709.

This invention relates to the art of hydraulic control systems, more particularly of the type to effect remote control of the rudder shaft of a ship.

As conducive to an understanding of the invention, it is noted that the rudder shaft of a ship, especially when the ship is large, requires considerable force for actuation thereof through an appreciable range of movement and with sufficient rapidity to take care of emergencies when the ship is traveling at high speed and the course of the ship must be rapidly changed.

Where such force is supplied by a high torque motor operatively connected to the rudder shaft and which is energized by a power source having a motor driven pump which feeds the motor, due to the kinetic energy of the heavy moving rudder, even when the power source is turned off the rudder continues its movement for an additional amount.

This additional movement, although not critical when the ship is on the high seas with ample room in which to maneuver can be extremely dangerous when the ship is in a confined area such as when it is in a harbor.

It is accordingly among the objects of the invention to provide a hydraulic control system which is relatively simple in construction and dependable in operation and which will provide a step by step movement of the rudder with substatially no overshoot from the desired setting of the rudder with controllable variations in the rate at which such step by step movement can be eifected, and will also provide rapid movement of the rudder shaft over a controlled range when the ship is traveling at high speed and with a simple operation will permit rapid movement of the rudder shaft over full range when the ship is moving at low speeds such as when docking.

Another object is to provide a system of the above type which may be electrically operated to effect the desired steering action in case of failure of the manually operated telemotor normally used for steering action or where it is desired to use an automtic pilot for steering.

According to the invention, these objects are accomplished by the arrangement and combination of elements hereinafter described and more particularly recited in the claims.

In the accompanying drawings in which are shown one or more of various possible embodiments of the several features of the invention.

FIG. 1 is a diagrammatic view of one embodiment of the invention,

FIG. 2 is a view similar to FIG. 1 of another embodiment of the invention similar to that shown in FIG. 1 in which one of the two hydraulic rotary motors driving the rudder shaft is replaced by a plurality of linear actuators, and

FIG. 3 is a detail view on an enlarged scale of one of the linear actuators utilized in the embodiment of FIG. 2.

Referring now to the drawings, the embodiment shown in FIG. 1 is especially designed for large ships and the rudder shaft 11 has secured thereto a rudder bar and hydraulic motors '12 and 13, the latter having a much greater torque output than the former.

.The motor 13 has ports 14, 15 connected by lines 16, 17 to ports 18, 19 of a valve 21. The valve 21 is of conventional type being spring returned to open center neutral position and having two operating positions on each side of the neutral position respectively. The valve 21 has additional ports 22, 23 and a control member adapted in neutral position to close said ports 18, 19 and connect ports 22, 23 and in either extreme position to connect ports 19, 22 and 18, 23 or ports 18, 22 and 19, 23, A similar valve 21 is provided having ports 18, 19, 22, 23' adapted to be connected in similar manner as the ports of valve 21.

The control members of valves 21, 21' are connected respectively by rods 24, 24 to links 25, 25, which are pivotally connected at 26 adjacent the end 27 of a lever 28, the latter being pivotally mounted to a fixed support as at 29.

The ports 18, 19' are connected respectively to the ports 31, 32 of a hydraulic actuator 33 on each side of the piston 34 thereof. The end of the cylinder of actuator 33 is pivotally mounted to a fixed support as at 35 and the piston rod 36 thereof is pivotally connected to the end of rudder bar 10 as at 37.

In order to actuate the small motor 12, a fluid pressure source 41 is provided. This source comprises a telemotor which may be mounted on the bridge of a ship and has a steering wheel 42 for actuation thereof.

The telemotor has ports 43, 44 connected by lines 45, 46 to the ports 47, 48 of motor 12 and by lines 49, 51 to ports 52, 53 of atvalve 54 which is solenoid actuated and spring returned. The valve 54 has two additional ports 55, 56 and a valve member controlled by solenoid 57. The valve 54 is normally retained by spring 58in position to connect ports 52, 55 and ports 53, 56 and when solenoid 57 is actuated connects ports 52, 53 through passageway 59 and ports 55, 56 are connected through the annular chamber C.

The ports 55, 56 are connected to ports 61, 62on each side of the piston 63 of an actuator 64, the piston rod 65 of which is pivotally connected through link 66 to lever 28 as at 67. The piston rod 65 also mounts a piston 68 which is of slightly smaller diameter than piston 63 to provide clearance between the periphery of piston 68 and the wall of the casing of actuator 64, in the illustra tive embodiment shown a small diameter is provided through piston 68.

The ports 23, 23 of valves 21, 21' are connected respectively to sections A and C of reservoir 71 of power source S. The ports 22, 22 to the outlet of motor driven pumps 74, 75, the inlet of said pumps being connected to said reservoir sections A and C. In addition, a third constantly operating motor driven pump 76 is provided, having its inlet connected to section B of said reservoir and its outlet connected to line 77 which in turn is connected to lines 72, 73, one-way valves 78 in said line 77 preventing flow from pumps 74, to pump 76.

in order electrically to control the system, an electric switch 81 is provided which illustratively is hand operated by control handle 82, but could be automatically operated by a conventional automatic pilot system.

The switch 81 is electrically connected by lead 83 to a motor M which drives a pinion 84 that engages a rack bar 85 which is pivotally connected through a link 86 to lever 28 and will effect movement of the lever in either a clockwise or counterclockwise direction depending upon the direction of movement of handle 82.

The lower end 27 of lever 28 which is connected to ground, is normally positioned midway between contacts 86 and adapted to engage either of these contacts when lever 28 is pivoted in the manner to be described.

The contacts 86' are connected by leads 87 to a relay 88 that controls the energization of the motor of pump 74 and to solenoid operated valve 89 which controls passageway 69 are connected by lines 72, 73

flow from pump 75 and pressure accumulator 91 connected thereto.

In the operation of the system shown in FIG. 1, when steering wheel 42 is rotated, fluid under pressure will flow for example from port 43 through line 45 to port 47 of motor 12 and from part 48 through line 46 to port 44 of the telemotor 41.

The motor 12 has only a fraction of the torque output of motor 13, i.e., 500 inch-pounds vs. yard-tons for example and insuflicient torque is available to rotate shaft 11.

Fluid under pressure will flow from port 43 of the telemotor through line 49 and through connected ports 52, 55 of valve 54 into port 61 of actuator 64.

As the piston 68 of actuator 64 is aligned with the port 61, only small clearance is provided for the flow of fluid into actuator 64. As a result, the initial movement of piston 63 to the right will be slow until piston 68 has been moved clear of port 61. As the piston 63 is connected through piston rod 65 and link 66 to lever 28, and the lever 28 is connected to rods 24, 24' of valves 21, 21' which are spring retained in neutral position, no movement will be imparted to piston 63 until the pressure in line 49 has built up sufficiently to overcome the force exerted by the spring of valves 21, 21'.

With continued rotation of steering wheel 42, since motor 12 still will not rotate, the pressure will build up sufficiently to move piston 63 to the right, fluid returning from port 62 through ports 56, 53 of valve 54 to port 44 of the telemotor 41.

Movement of piston 63 to the right will cause clockwise movement of lever 28 and movement of rods 24, 24 of valves 21, 21' to the left. This will cause ports 18, 23 and 19, 22 of valve 21 to be connected and the corresponding ports 18, 23' and 19', 22' of valve 21 to be connected.

If the movement imparted to lever 28 is only slight due to slow rotation of the steering wheel, no circuit will be completed to contacts 86 by the end 27 of lever 28. As a result, pump 74 and valve 89 will not be actuated. However, fluid under pressure will flow from pump 76 through lines 77, 72, 73 to ports 22, 22' of valves 21, 21' and through ports 19, 19', which ports are only partially opened, to port 15 of motor 13 and to port 32 of actuator 33. As a result, clockwise movement will be imparted to shaft 11 by motor 13, and bar 10.

As the rudder shaft 11 is rotated as above described, the motor 12 will also rotate and as a result, cavitation will occur in the pressure line 49 connected to port 47 of motor 12. This cavitation will cause a pressure drop in line 49 with resultant drop in the pressure on the fluid reacting against piston 63. Consequently, the springs of valves 21, 21' will cause the lever 28 to be moved back to neutral position blocking further flow of fluid under pressure to the motor 13 and actuator 33. With continued rotation of the steering wheel 42, the pressure again builds up and consequently there is a step by step movement of the rudder shaft 11.

Clearly, the incremental movement of the rudder can be very small with slow rotation of the steering wheel and can be large with rapid rotation of the steering wheel.

If faster movement is imparted to the steering wheel 42 which may be required in an emergency, where rapid movement of say plus or minus 35 is required of the rudder in say 10 seconds, for example, against the same movement required in seconds under normal cruising operation, such greater movement will cause pivotal movement of lever 28 sufliciently so that the end 27 thereof engages contacts 86. As a result, the relay 88 controlling motor pump unit 74 will be energized to energize such motor pump unit and in addition, the solenoid valve 89 will be energized to provide communica tion between pressure accumulator 91 and line 73, the motor pump unit 75 being de-energized automatically by a conventional pressure switch when the accumulator 91 is charged.

As a result of the high pressure, large volume flow from the accumulator through line 73 and connected ports 22', 19' which are now fully open due to the extreme movement of lever 28, a large volume of fluid under very high pressure will be forced into port 32 of actuator 33 to effect rapid downward movement of the piston 34 thereof, thereby quickly moving the bar 10 and rudder shaft 11 in a clockwise direction in the illustrative embodiment shown, thereby effecting rapid swing of the rudder. Such rapid movement imparted to the rudder shaft 11 by bar 10 would tend to cause the rotary motor 13 to cavitate which would cause build-up of air in the lines with resultant impact and shock when the system was restored to normal operation. This is avoided however, by reason of the supply of fluid under pressure from pump unit 74 which is applied through connected ports 22, 19 of valve 21 to port 15 of motor 13 in addition to the flow from pump unit 76 which is totally diverted into port 22 by reason of the fact that the high pressure from accumulator 91 retains the associated one-way valve 78 in closed position.

Such combined pressure from pump units 74, 76 in addition to preventing cavitation in the system also supplies additional power to enhance the speed of rotation of the shaft 11 which has force applied thereto both from actuator 33 and motor 13.

It is to be noted that with the rudder in normal position, i.e., extending longitudinally of the longitudinal axis of the ship, the angle between the bar 10 and piston rod 36 illustratively is 90.

Thus, as the piston rod 36 moves downwardly for example, the actuator 33 will pivot in a counterclockwise direction about its pivot 35 and the pivotal connection 37 of the piston rod 36 and bar 10 Will move toward alignment with the axis of shaft 11 and pivot 35. As the pivot 37 moves closer to such alignment, the lever arm becomes smaller and smaller with the result that the torque imparted by actuator 33 to shaft 11 will progressively be reduced. Thus, for example, assuming that the pivots 35 and 37 become longitudinally aligned with shaft 11 with 80 rotation of the rudder shaft, the torque will progressively decrease from maximum to zero. This is important to prevent rapid swing of the rudder shaft through an 80 angle when the ship is proceeding at relatively high speeds; with the rudder at such position it would be damaged or broken. Due to the automatic reduction in torque by the geometry of location of the actuator 33, the helmsman cannot inadvertently, by rapid turning of the steering wheel 42, cause the rudder to move quickly, past, say :50 for the reduction in torque is such that the resistance of the rudder due to movement of the water against the rudder at high speed, will prevent such rotation.

Even though the pump units 74, 76 are still supplying fluid under pressure to motor 13, this alone will not cause rapid movement of the rudder since the pressure available from such units is only 25% for example of that available from the accumulator 91.

If, however, the speed of the ship is slow enough when it is being steered, there will be little resistance against the rudder and consequently even if torque applied to actuator 33 past, say, plus or minus 50, due to the reduced lever arm is low, the pressure available from pumps 74, 76 will be sufficient so that enough torque will be developed by motor 13 to rotate the rudder shaft through an angle of 80 which may be required for docking purposes.

The follow up movement effected by the small motor 12 will also take place in the same manner as previously described. However, in view of the rapid movement of the steering wheel, the incremental steps will be very large.

In the event the telemotor 41 should be disabled or where it is desired to switch an automatic gyro-pilot into circuit, the electrical control system shown in FIG. 1 may be employed. Thus, the helmsman can move the control handle 82 of switch 81 to the left or right as desired.

Assuming that it is moved in direction to cause motor M to rotate in a counterclockwise direction, it will cause the rack bar 85 to move to the right and also will energize solenoid 57. The energization of solenoid 57 will cause ports 52 and 53 to be connected to short circuit the telemotor and motor 12, and will cause ports 55, 56 to be connected to short circuit actuator 64.

As a result of the movement of the rack bar 85 to the right, the lever 28 will be pivoted in a clockwise direction to effect the actuation of valve 21, 21' as previously described.

The embodiment shown in FIGS. 2 and 3 which is also designed for the rudder shafts of large ships, is similar to the embodiment of FIG. 1 and corresponding parts have the same reference numerals primed. The shaft 11 of the rudder has secured thereto a very small torque hydraulic motor 12 having a torque output in the order of say a few hundred foot-pounds.

In order to apply a great torque to the shaft 11' in the order of say 500 foot-tons, for example, a plurality of hydraulic actuators 101A, B, C, D are provided. Those actuators are operatively connected to the shaft 11 so that when energized each will apply rotary force to the shaft in the same direction, thereby giving the total effect of the force exerted by the four actuators.

In the illustrative embodiment herein shown, the ac tuators 101 are identical and hence only one will be described in detail.

I Each of the actuators comprises a cylinder 102 pivotally mounted at one end as at 103 on a fixed support. Each actuator has a piston '4 slidably mounted therein to which is secured one end of a piston rod 105. In order to operatively connect the piston rods 105 to the shaft 11, an actuating plate 106 is secured to the shaft 11'. As shown, the plate is substantially rectangular in configuration, of greater length than width with the ends of each actuator being connected to the corners of the plate as at 107.

The hydraulic actuators 101 are so positioned with respect to the rudder shaft 11 that in the neutral position of the rudder when it is longitudinally aligned with the longitudinal axis of the ship, lines drawn from the longitudinal axis of the shaft 11 to the pivotal axis 103 of each of the actuators 101 will define angles of 90 therebetween.

1 In the illustrative embodiment shown, a line drawn from each of the pivot corners 107 of the pivot plate 106 to the pivotal axis 103 of each actuator 101 will define an angle of say 15 with respect to the line drawn from such pivotal axis 103 to the shaft 11'.

With this arrangement, it is apparent that if, for example, the pistons 104 of actuators 101A and 101D moved outwardly, and the pistons of actuators 101B and 101C are moved inwardly simultaneously, the sum of the forces provided by such four actuators will provide torque to rotate the shaft 11 in a counterclockwise direction.

Each of the actuators carries a cam bar 108 which is designed to cooperate with the projecting end 109 of the valve member ofa conventional distributor valve 111 secured in fixed position with respect to the pivotally mounted actuator 101. The valve 111is designed in one position when the end 109 is restrained by bar 108 to conmeet its ports 112, 115 and 114, 113 and in another position when the cambar 108 has moved away from the end 109 to connect ports 112, 113 and 114, 115.

The ports 113, 115 of the valves are connected to ports 116, 117 of the actuator on each side of the piston 104 thereof.

The ports 114, 112 'of actuators 101A and B respec tively are connected to line 119. The ports 112, 114 of actuators 101A and B respectively are connected to line 118. The ports 112, 114 of actuators 101C, D respectively are connected to line 122. The ports 114, 112 of actuators 101C and D respectively are connected to line 121.

The ports 47 and 48 of motor 12 are connected by lines and 46 to the ports 52 and 53 of a solenoid operated disconnector valve 54' identical to the valve 54 6 shown in FIG. 1. In addition, the lines: 45' and 46 are connected by lines 49 and 51 to the ports 43 and 44 of a telemotor 41' which is controlled by steering wheel 42" The ports 55 and 56 of valve 54 are connected to ports 61 and 62 of a hydraulic actuator 64 which is identical to the actuator 64 shown in FIG. 1. The control rod 65 of actuator 64 is pivotally connected through a link 66 to lever 28 pivotally mounted as at 26 to a fixed support. Also pivotally connected to the lever28through a link 86 is a rack similar to the rack 85 shown in FIG. 1 and driven by a pinion 84 on a electric motor M. The end of rod 65 protruding from the actuator 64 carries a contact finger 123 adapted to engage either of fixed contacts 80 upon suificient movement of said rod, the electrical circuit completed by engagement of the contact finger with the contacts being hereinafter described.

The lever 28 is connected to valves 21a and 21a identical to the valves 21, 21 shown in FIG. 1. The ports 18' and 19 of valve 21a are connected to lines 119 and 118 respectively and the ports 18 and 19 of valve 21a connected to lines 122, 121 respectively. The ports 23, 23 of valves 21a and 21a are connected respectively to chambers A and C of a reservoir 71, which forms .part of the power source S, said chambers being defined by vertical partitions 124 in said reservoir of height less than the height of the reservoir. The ports 22 and 22 of valve 21a, 21a are connected by lines 72 and 73 to junctions 125, each junction being connected to one side of an unloader valve 125, the other side of which is connected by line 127 to chambers A and C of the reservoir. The junctions are also connected to lines 128 and through one-way valves 129 to the outlet of a motor driven. pump 131, 132 and to the inlet of the unloader valve. In addition, the lines 128 are connected through one-way valves 133 to outlet port 135 of a solenoid control valve 136, the inlet 137 of said valve being connected to the port of a high pressure accumulator 138 and to a motor driven pump 139 of much higher pressure than the pumps 131 and 132. The inlet of pumps 131 and 132 are connected to chambers A and C and the inlet of pump 139 is connected to chamber B between the partitions 124.

Means are provided electrically to control the movement of the rudder shaft for actuation thereof. To this end, as shown in FIG. 2, an electric actuator 141 is provided on the bridge of a ship, for example, which is controlled by a wheel 142. The actuator is electrically connected to the solenoid 57 of valve 54 and .to electric motor M which is of the reversible type. Thus, regardless of the direction of movement of the wheel 142, of

actuator 141, the solenoid valve 54 will be energized to effect movement of the valve member thereof to the right against the force exerted by the spring thereof to short circuit the lines from the motor 12 and telemotor 41 so that such units are effectively out of circuit and depending upon the direction of movement of the wheel of electric actuator 141, the rack 85 will be moved either to the left or right to pivot the lever 28 in the corresponding direction. 7

Normally, with slight movement of the wheel 42 the high pressure source provided by accumulator 138- and pump 139 is not in circuit. When relatively large movement of the rudder is desired, the contact arm 123 will engage either fixed contact 80 to complete a circuit to solenoid valve 136 so that high pressure will be supplied through such valve from the accumulator 138.

In order to prevent application of such high pressure when the rudder has moved through an angle of say greater than 40", a relay 151 is provided having switch contacts 151 in lead 152 connected between contacts 80 and valve 136 which will be open through engagement of movable contact arm 153 and fixed contacts 154 at such desired angle of position of the rudder.

In the operation of the system shown in FIGS. 2 and 3, when steering wheel 42 is rotated. fluid under pressure will flow, for example, from port 43' through line 49' to port 47 of motor 12 and from port 48' of the motor through line 51' to port 44' of the telemotor. As the motor 12' has only a fraction of the torque output provided by the four actuators 101, i.e., 500 inch-pounds as compared to 20 yard-tons, for example, insuflicient torque is available to rotate shaft 11'.

Fluid under pressure will also flow from port 43' of the telemotor through line 49' to port 52' of valve 54 and as the valve is in the position shown in FIG. 1, such fluid will flow through port 55 of the valve 54' to port 61' of actuator 64, causing the piston 63 thereof to move to the right. Due to the fact that the port 61' of actuator 54' is restricted by the piston 68 associated therewith, fluid will flow relatively slowly at the outset. As the piston 63 of actuator 64 is connected through link 66' to lever 28, the latter will be pivoted in a clockwise direction from the position shown in FIG. 2 to effect movement to the left of the rods 24, 24' of valves 21a and 21a which are spring retained in neutral position as shown in FIG. 1.

Due to the force exerted by the springs associated with valves 21:: and 21a, no movement will be imparted to the lever 28 until the pressure in line 49' from the telemotor has built up sufficiently to overcome the force exerted by the springs of valves 21a and 21a.

With continuous rotation of steering wheel 42' since the motor 12' will still not rotate, the pressure in line 49 will build up sufficiently to move piston 63 of actuator 64', to the right as above set forth.

Movement of piston 63 to the right will cause clockwise movement of lever 28' which will cause the ports 19', 22' and 18', 23 of valve 21a to be connected and the corresponding ports 19, 22' and 18' and 18, 23' of valve 21a to be connected.

If the movement imparted to lever 28 is only slight due to slight rotation of the steering wheel, no circuit will be completed to contacts 80 by the contact 123 of hydraulic actuator 64'. As a result, solenoid valve 136 of the power source S will not be actuated and at this time the accumulator 138 and pump 139 will not be in circuit.

However, fluid under pressure will flow from pumps 131 and 132 through one-way valves 129, lines 128, 72', 73 to the ports 22' and 22 of valves 21a and 21a and due to the connection of the ports of the valves as above described, the fluid under pressure in line 118 will flow into ports 112, 114 of the valves 111 of actuators 101A and B respectively and from line 121 to ports 114, 112 of the valves 111 of actuators 101C and D.

As the valves, when the rudder is longitudinally aligned with the longitudinal axis of the ship will have their ports 112, 115 and 114, 113 respectively in communication, the fluid under pressure will react against the pistons of the respective actuators 101A, B, C and D so that the pistons of the respective actuators 101A and D will be moved outwardly and the pistons of actuators 1013 and C will be moved inwardly.

As a result, the four actuators will transmit torque in the same direction with respect to the rudder shaft 11 to effect rotation of said rudder shaft with the torque available resulting from the action of pumps 131 and 132.

It is to be noted that when the rudder shaft rotates say in a counterclockwise direction, the pivotal axes 103 of the actuators 101B and C and the pivots 107 of the plate 106 will .be aligned with the axis of shaft 11' and hence at this instance no torque will be imparted to the shaft by the actuators 101B and C and only the actuators A and D would be applying torque. However, due to the rotation of shaft 11, the cam bars 108 of actuators B and C would move away from the ends 109 of the actuators of the associated valves 111 so that said valves would automatically switch, connecting their ports 112, 113 and 114, 115. As a result, the fluid under pressure would now be applied in direction to move the pistons of actuators B and C outwardly so that at this time all four actuators would have their pistons moved outward- 3 1y to apply the total torque from such actuators to the rudder shaft 11.

It is apparent therefore that at all times all four actuators 101 are utilized to apply torque to the shaft 11' except at the fraction of a second during which the valves of actuators B and C are switching which have no effect on the steering action.

Due to the geometry of the system, it is apparent that the rudder shaft can move through an angle of at least plus or minus 90 for precision maneuverability of the ship such as is required when docking.

As the rudder shaft is rotated, as above described, the motor 12 will also rotate and as a result cavitation will occur in the pressure line 49 connected to the port 47 of the motor. This cavitation will cause a pressure drop in line 49' with resultant drop in the pressure on the fluid reacting on piston 63 of actuator 64. Consequently, the springs of valves 21a and 21a will cause the rods 24, 24"to react against the lever 28 which will be restored to neutral position blocking further flow of fluid under pressure to the actuators 101. With continued rotation of the steering wheel, the pressure again builds up and consequently there is a step by step movement of the rudder shaft.

Clearly, the incremental movement of the rudder can be very small with slow rotation of the steering wheel and can be large with rapid rotation of the steering Wheel.

If faster movement is imparted to the steering Wheel which may be required in an emergency where rapid movement of the rudder is required, Where, for example, the ship is moving at high speed with the water offering great resistance to the rudder, it is necessary in order to effect such rapid movement of the rudder that much greater torque be available than is required during routine steering action.

Such torque is automatically applied by the system herein described.

Thus, with rapid movement of the steering wheel, the pressure in line 49' applied to port 61' of the actuator 64' will rapidly build up to effect rapid and total movement of the piston 63 so that the contact member 123 will engage contact completing a circuit to the solenoid valve 136 of the power source.

As a result, fluid under high pressure stored in the accumulator 138 will flow to line 128, through one-way valves 133, to the ports 22' and 22 of valves 21a and 21a. Since the pressure from accumulator 138 is much greater, i.e., four times that from either of the pumps 131 and 132, it is apparent that the check valves 129 will prevent flow to such pumps which might otherwise be injured. Such sudden application of high pressure from the accumulator will be applied through valves 21a and 21a to the four actuators 101 to effect extremely rapid movement of the pistons thereof due to the greater pressure applied thereto so that the rudder will quickly respond to the steering action.

It is apparent that the followup system effected by the small motor 12 will also take place in the same manner as previously described. However, in view of the rapid movement of the steering wheel and hence of the pistons, the incremental steps will be very large.

It is of course to be noted that When the one-way valves 129 are closed, as above described, it is necessary that the pumps 131 and 132 which are continuously operating, be discharged to the reservoir and this is accomplished by the conventional unloader valves 126.

It is to be noted that although such high torque provided by the accumulator is desired in an emergency for rapid movement of the rudder, it is also essential that Y the rudder not be moved with high torque when it has passed an angle of say plus or minus 40 when the ship is moving at high speed which might break the rudder.

This is accomplished in the embodiment of FIG; 2 by the contact arm 153 which engages fixed contact 154 when the rudder shaft has moved through an angle of plus or minus 40, for example.

When this occurs, an electric circuit is completed to the coil of relay 151 to open the contacts 151 in the circuit to the solenoid valve 136 of the high pressure source.

As a result, the solenoid valve 136 will close to cut off application of fluid under high pressure from the accumulator 138 and hence only the pumps 131 and 132 which apply fluid under relatively low pressure as compared to that from accumulator 138 will be available to effect movement of the pistons of actuators 101.

It is to be noted that when the ship is being docked and is moved at very slow speeds, it is desirable that the rudder be capable of moving through angles in excess of plus or minus 40 and for this purpose a switch S is provided in the circuit to relay 151 which is open when the ship is being docked so that the relay 151 will be out of circuit.

In cases where the hydraulic telemotor 41 is not operative, or it is desired to eifect steering action either manually by an electric control or automatically by an automatic pilot such as a Sperry automatic pilot, the electrical system shown in FIG. 2 is provided. This system may comprise the electric actuator 141 controlled by wheel 142. The actuator 141 is connected to reversable motor M which will turn in one direction or the other depending upon the direction of rotation of the wheel of the electric actuator. As the operation of the motor M has been previously described with respect to the embodiment of FIG. 1, it will not be described.

As shown in FIGS. 1 and 2, it is to be noted that the actuating means driving the rudder shafts 11, 11' involves two systems in each embodiment, Thus, for example, as shown in FIG. 1, the hydraulic motor 13 and the hydraulic actuator 33 drive the shaft 11. The hydraulic motor 13 will return fluid to the reservoir chamber A and the actuator 33 will return fluid to reservoir chamber C. In each case when the level of the fluid in each chamber A and C rises above the upper edge of the associated partitions Y that define the chamber B, such fluid will flow into the chamber B. It is apparent therefore that the minimum level of the fluid in chambers A and C will be defined by the height of the associated partition.

If there should be a break in the fluid lines connected to either the motor 13 or actuator 33, say, for example, in the lines associated with actuator 33, it is apparent that the level of the fluid in chamber C will quickly drop below the upper edge of the associated partition Y and the chamber C will empty. At the same time since the pump 76 is operating, the level of fluid in chamber B will start to drop, since it will only be replenished by the fluid from chamber A that flows over the upper edge of the associated partition X. Thus, since the pump 76 is discharging into the hydraulic actuating system including the actuator 33, which is leaking, the chamber B will also empty and the pump 76 will have no useful effect. In view of the oneway valve 78, the pump 74 will not discharge fluid past said valve and the pump 74 will continue to operate effectively since the chamber A will be replenished by the return line from motor 13.

As a result of the foregoing, it is apparent that in normal operations, the three pumps or fluid sources 74, 75, 76 will supply the system as previously described. In the event of breakdown of the hydraulic lines to either the motor 13 or the actuator 33, there will always be one source of fluid under pressure fully available.

The same principle is also true with respect to the fluid reservoir means of FIG. 2,.

As many changes could be made in the above constructions, and many apparently widely different embodiments of this invention could be made without. departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described our invention what we claim as new and desire to secure by Letters Patent of the United States is:

1. A hydraulic control system for effecting rotary movement of a shaft on each side of a neutral position, comprising a pair of hydraulic actuating means each operatively connected to said shaft to rotate the latter, fluid reservoir means having three fluid storage regions, three motor actuated sources of fluid under pressure, each having an inlet connected to an associated fluid storage region and an outlet, the outlets of two of said sources being connected respectively to an associated hydraulic actuating means, the outlet of the third source being connected to the outlets of each of said first two sources, each of said actuating means having a fluid return port connected respectively to an associated fluid storage region, means to provide a minimum level of fluid in each of said last two fluid storage regions and to feed said third fluid storage region with fluid from said last two fluid storage regions above such minimum level, valve means controlling How of fluid from said first two sources to the associated hydraulic actuating means, and means to actuate said valve means.

2. The combination set forth in claim 1 in which one of said three to actuate said valve means places said cut off source in circuit upon actuation of said valve means a predetermined amount.

3. The combination set forth in claim 2 in which one of said first two sources is normally cut off.

4. The combination set forth in claim 2 in which said third source is normally cut off.

5. The combination set forth in claim 1 in which a manually operable fluid pressure source is operably connected to said valve means to actuate the latter.

6. The combination set forth in claim 1 in which an electrically operable control means is operably connected to said valve means to control the latter.

7. The combination set forth in claim 1 in which a manually operable fluid pressure source is operably connected to said valve means to control the latter, an electrically operable control means is operably connected to said valve means to control the latter and means are provided to bypass said manually operable fluid pressure source when said electrically operable control means is actuated.

N 0 references cited.

MARTIN P. SCHWADRON, Primary Examiner. R. R. BUNEVICH, Assistant Examiner.

sources is normally cut off and the means 

1. A HYDRAULIC CONTROL SYSTEM FOR EFFECTING ROTARY MOVEMENT OF A SHAFT ON EACH SIDE OF A NEUTRAL POSITION, COMPRISING A PAIR OF HYDRAULIC ACTUATING MEANS EACH OPERATIVELY CONNECTED TO SAID SHAFT TO ROTATE THE LATTER, FLUID RESERVOIR MEANS HAVING THREE FLUID STORAGE REGIONS, THREE MOTOR ACTUATED SOURCES OF FLUID UNDER PRESSURE, EACH HAVING AN INLET CONNECTED TO AN ASSOCIATED FLUID STORAGE REGION AND AN OUTLET, THE OUTLETS OF TWO OF SAID SOURCES BEING CONNECTED RESPECTIVELY TO AN ASSOCIATED HYDRAULIC ACTUATING MEANS, THE OUTLET OF THE THIRD SOURCE BEING CONNECED TO THE OUTLETS OF EACH OF SID FIRST TWO SOURCES, EACH OF SAID ACTUATING MEANS HAVING A FLUID RETURN PORT CONNECTED RESPECTIVELY TO AN ASSOCIATED FLUID STORAGE REGION, MEANS TO PROVIDE A MINIMUM LEVEL OF FLUID IN EACH OF SAID LAST TWO FLUID STORAGE REGIONS AND TO FEED SAID THIRD FLUID STORAGE REGION WITH FLUID FROM SAID LAST TWO FLUID STORAGE REGIONS ABOVE SUCH MINIMUM LEVEL, VALVE MEANS CONTROLLING FLOW OF FLUID FROM SAID FIRST TWO SOURCES TO THE ASSOCIATED HYDRAULIC ACTUATING MEANS, AND MEANS TO ACTUATE SAID VALVE MEANS. 